JamesNH

iTrader: (12)

Im having hard starts due to low fuel pressure and other pressure related problems and have found that the problem seems to be electrical.

What i was wondering would the relay be the problem if the voltage with the key on acc at the fuse goes to 12v then almost immediately drops to 6-8volts than to 0volts? I have already swapped in what seemed to be a good relay that seemed to be identical.

Please post only information related to the voltage.

-James

JamesNH

iTrader: (12)

bump......

MIXXMAX

iTrader: (1)

Have you change your fuel filter lately? I would think if you are having low fuel pressure, I would start from there.

njmodi

iTrader: (4)

A relay won't cause a voltage drop, it's an on/off type function (for a relay).

How do you know you have low fuel pressure? Have you checked with a pressure gauge?

I would suspect a bad pump or regulator (more likely a bad pump).

JamesNH

iTrader: (12)

Filter is new so thats Good. Pressure low with line pinched after inline pressure gauge but before regulator only goes to 30 ish but disapears if un pinched. 0psi on startup. Pump measured 1 ohm which is within spec per the FSM.

njmodi

iTrader: (4)

When you first start the car the pump is supposed to turn on for a few seconds to rebuild fuel pressure... the fuel pressure is supposed to be around 40psi IIRC... I say you have a bad pump...

JamesNH

iTrader: (12)

Bump

Cause i thought resistance was a sure way of telling of pump life.

njmodi

iTrader: (4)

Resistance may determine if the pump has shorted out completely, but not sure you'll be able to detect a drop in overall performance...

Mishmosh

iTrader: (3)

James,
What is the psi when you turn the ignition to ACC? If it jumps to a low psi, it is a pump problem. If the residual psi in the fuel line does not change, it could be the pump is not getting a signal or the pump may have failed almost completely.

Edit: IIRC, fuel pressure spikes to about 43psi on turn on and within seconds drops down to a steady state of around 38psi.

JamesNH

iTrader: (12)

yeh its at 0psi if the line isnt pinched after the gauge otherwise its at 34psi. picnhed. But pinched or not it never reaches that 43psi.

Ive been thiniking its the pump for a long time but i keep finding things that make me stray.

Mishmosh

iTrader: (3)

I'm not getting why it's 0psi when the fuel line is not obstructed. If the pump is putting out any kind of pressure, it has to build up somewhere unless there is a massive fuel dump somewhere. Regardless, even if you occlude the line after the guage, you get subpar numbers which really makes the fuel pump suspect.

Good luck with that. Don't blame you for trying to double check your testing logic--I hate it playing the parts swap game...

i30krab

iTrader: (1)

Try hot wiring the pump directly to yor battery!
Take out rear seat and open cover to get at wires. get a 30 amp relay and use the oem harness wire from the stock relay and trigger the new relay with this wire. .
• 30 - feed wire from battery
• 87 - when cutting stock 12V pump wire, this is to the end that goes into the pump
• 86 - when cutting stock 12V pump wire, this is to the end that goes into the harness in the fender area
• 85 - ground wire to chassis

JamesNH

iTrader: (12)

Heres an update the rewire helped get the pressure up with the line crimped. I also found out that I have pressure bleeding off in the rear which could be the injectors or regulator. But the car runs smoother and seems to have better acceleration.

Also don’t use radio shack relays they suck. I went and bought one that was dead then search online and found out that they like to do that. Also I saved 4$ by just picking one up at an audio place.